Posts Tagged ‘xen’

IMHO one of the great benefits of virtualization is the ability to properly size your guests. Many times 512M memory and an 8G / is plenty. Increasing memory for a virtual machine is typically pretty straight forward, but there are several options when adding disk space. Mounting the space in the file system and doing something with LVM are likely the most common paths.

Depending on the situation I typically lean toward keeping my small 8G root and mounting extra storage where needed in the file system. I think its the simplest solution for most cases. I don’t like ending up with a bunch of mounts, so in the cases where storage needs are spread across the file system growing the root becomes important. You can add a new virtual disk, partition it, toss it into the Volume Group and then extend your volume and file system. There is absolutely nothing wrong with this approach but having all those virtual hard drives attached just seems a bit hap-hazard and messy. When I need more space at / I think its much cleaner to just extend the partition that is in the VG of my systemroot. Anyway here are my notes. The block devices are specific to Xen but the actions should work on other platforms and on bare metal. My default partitioning scheme is as follows, /dev/xvda 2 partitions, 100M /boot, LVM with / being comprised of the full available space. Swap is on /dev/xvdb. This allows me to keep growing xvda and extending the second partition when I need to add space.

1. Power vm off
2. Create snapshot incase things go horribly wrong
3. Extend virtual drive size
4. Power vm on
5. Fdisk device (/dev/xvda)
6. Delete last partition
7. Create new partition using default values
8. Reboot vm
9. Resize LVM Physical Volume (pvresize /dev/xvda2)
10. Resize Logical Volume to fill new space (lvresize -l 100%VG /dev/VolGroup00/systemroot)
11. Resize filesystem (resize2fs /dev/VolGroup00/systemroot)
12. Reboot for good measure
13. Delete snapshot

I am sure you are aware of my affinity for the Xen hypervisor. In the last year I have switched over to Citrix Xenserver. With other people managing VMs as well having a nice GUI is helpful. One of my complaints is that the GUI (XenCenter) is a windows only app. Common Citrix, please release a cross platform management console. I’ve got to run a windows VM just to use the GUI (granted I don’t have to use the gui, there is a nice API and console utilities). At any rate today I noticed that I could no longer pull up the console for a windows VM nor could I pull up the performance metrics available in XenCenter. A few searches turned up Kenneth Hunts blog and a post that showed me where to fix it. (more…)

I am so very tired of hearing about “the cloud”. Over lunch the other day a co-worker decided we should just call it the phog instead since the phog does a better job of describing exactly what is meant by the cloud.

Why is phog a better description? The phog has no defined shape, you can’t see clearly in it, its different everywhere you go, and once your in the middle of it you can’t find your way out (due to marketing fluf).

You cant have escaped all of the cloud stories in the past year or so. The one that just sent me over the edge was a press release about Vmware buying SpringSource. It is basically Vmwares approach to supplant Xen as the major phog platform. I’m not sure exactly what rubbed me wrong and sent me off into this tirade. Its very possible that I just don’t like Vmware and the first article I read used the more popular term for phog putting me in this tizzy. It’s also possible that I was already on edge about Vmware after my recent discussions with one of their sales people.

For a bit of background Vmwares sales goons are spreading the F.U.D. hard core. One sales goon recently told me “Xen is dead in the water”, “No one is using Xen”, “With all of Citrix’s advertising about Hyper-V  they don’t seem commited to the Xenserver product”. That along with “Everyone is going to KVM”, and some other slams about Xen not having dom0 support in mainline. Of course its fine that I don’t even have the option of running the Vmware hypervisor on the distribution of my choice, and no mention of the fact that dom0 support being mainline really has nothing to do with a Citrix products future. It’s not just a sales guy, I saw a similar slide against Citrix for their work with Hyper-V in a Vmware pdf (See bottom right corner). Anyway, on with the original rant.

As I was saying I was already on edge, and one more phog article shows up. What is the phog? Really? Its hosted applications, no more. Maybe a more programmatic way to define what services you would like and when you would like them available, but its nothing more than paying someone else to host your application servers.

This brings me to another point, and another thing that I wish developers would learn from system administrators (see my comment on Matt Simmons blog for context). Many of my developer friends think its perfectly fine to host everything on someone else’s equipment out in the phog. I feel it is one of my responsibilities to keep data safe. How can you keep data safe when its all out floating around in the phog. I have nothing against scaling out to the phog especially for high volume times but I still think that your core infrastructure should be managed on your own equipment where you can walk up to it and touch it if you want (even if its in someone else’s data-center).

I even had a conversation with a new co-worker recently who thinks everything, your data, downloaded content, desktop etc … will all move to the phog eventually. Ewwwww I can’t fathom letting my data slip that far from my hands.

Do you really think the phog will take off long term? What do you think about most of my developers friends points of view that putting _everything_ in the phog is acceptable or even a good idea?
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Today Citrix announced that it will distribute its enterprise packaging of Xen for free. This brings fancy gui management and features available in VMwares ESX server to everyone. (Actually I’m not clear if just the ability is there or if they actually are letting the gui go as well.)

This is not a scaled down, limited version of the hypervisor. From the end of March on, there will be only one edition of XenServer which and it will be free.

The ability to manage multiple hosts via XenCenter, live migration via XenMotion, and resource sharing pools are all included in this free release.

Read the press release here.

I can’t wait to see what VMware does in response.

A few days ago I finally got my copy of Running Xen. I was anxious to see how the information would be presented. I can tell you I was not disappointed. (more…)